The subject matter disclosed herein relates generally to multi-head nuclear medicine (NM) imaging systems, and more particularly to multi-head NM imaging systems that are capable of selectively moving the detector heads relative to an object, such as a patient, within the multi-head NM imaging system.
In NM imaging, such as single photon emission computed tomography (SPECT) or positron emission tomography (PET) imaging, radiopharmaceuticals are administered internally to a patient. The radiopharmaceuticals emit radiation that may be captured by an NM imaging system to generate images for diagnostic review. An NM imaging system may be configured as a multi-head system having a number of individual detector assemblies. The detector assemblies may include a movable arm that is capable of moving radially-inward toward the patient and a detector head that is held by the movable arm. A positioning sub-system of the NM imaging system controls movement of the detector heads in order to position the detector heads and acquire images of a designated region-of-interest (ROI). For example, the detector heads may be positioned within a few centimeters from the patient to acquire images of the heart of the patient.
The patient is typically confined within a cavity (e.g., bore) of the NM imaging system during the imaging session while the detector heads are positioned relative to the patient. Prior to the imaging session in which the diagnostic images are obtained, the patient is positioned relative to the detectors so that a collective field-of-view of the NM imaging system includes the anatomical region of interest (e.g., heart, brain, etc.). At this time, one or more persistence images are obtained and reviewed to position the patient. The persistence images are typically only used to position the patient and, as such, have a lower quality than the images used for diagnosis. Persistence images may also be referred to as scout images. As the images are acquired, the technician reviews the images and incrementally moves the patient within the cavity of the gantry so that the anatomical region-of-interest is within the collective field-of-view. It is generally desirable to quickly position the patient, because the emissions from the radioisotopes reduce over time. During the time in which persistence images are acquired, a technician may also assess the activity of the radioisotopes for determining the scan duration. In a traditional single or dual head SPECT camera, when imaging the torso, such as in cardiac imaging, the patient is instructed to hold his hand above his head. This is done to allow the large detector heads to come closer to the torso as the detector heads rotate about the patient. To some patient this cause discomfort or may be impossible for patients with limited mobility.
The quality and reliability of the diagnostic images depends upon the number of emitted photons detected by the detector heads. As such, it is desirable to position the detector heads relative to the patient so that more photons may be detected. While the method described above can be effective, other methods that enable positioning the patient more quickly and/or acquiring photons at a greater rate are desired.